Ammonia-assisted synthesis of gypsophila-like 1T-WSe2/graphene with enhanced potassium storage for all-solid-state supercapacitor

Transition metal dichalcogenides (TMDCs) with electrocatalytic properties have become the focus in the energy storage field. However, the storage ability of TMDCs is considerably limited by their poor electrical conductivity, because the lamellar structure tends to form irreversible agglomerates after several cycles. Herein, an ammonia-assisted synthesis of a gypsophila-like 1T-WSe2/graphene is conducted. Through adjusting different growth conditions, the gypsophila-like nanostructure is controllable. Electrochemical measurements indicated that gypsophila-like 1T-WSe2/graphene exhibits an outstanding specific capacitance of 1735 F g(-1) at 1 A g(-1), and the 1T-WSe2/graphene all-solid-state supercapacitor shows ultrahigh energy density (48.2 Wh kg(-1) at 250 W kg(-1)). After research, ammonium stabilizes the 1T phase, and generates a small amount of ammonia bubbles in the alkaline solution to prevent the structure collapsing during the electrode operation. Furthermore, the performed experiments and density functional theory (DFT) calculations confirm that a decrease in the electron localization near the Fermi level of 1T-WSe2 enhances electrical conductivity, and the absorption capability of potassium by 1T-WSe2 is three times that of H-2-WSe2. The result shows the gypsophila-like 1T-WSe2/graphene is highly attractive for the development of advanced electrodes for energy storage devices.

Automated summary

Transition metal dichalcogenides (TMDCs) with electrocatalytic properties have attracted significant attention in the energy storage field. A novel ammonia-assisted synthesis of gypsophila-like 1T-WSe2/graphene was conducted, showing outstanding electrochemical performance and potential for advanced electrode development.